Presentation “Is There Value-Added With Dynamic Regional Downscaling?”

Last evening I gave the following presentation via skype;

Pielke Sr., R.A. 2011: Is There Value-Added With Dynamic Regional Downscaling? Final Workshop of the S5-3 Project, Tsukuba, Japan, October 18,  2011.

In it, my conclusion was that regional downscaling from multi-decadal global climate models predictions to provide forecasts of climate impacts (what I define as a Type 4 downscaling) is a waste of funds (and worse, as it is misleading policymakers). 

We also present discuss the flaws in this type of downscaling (as well as define  four types of downscaling) in our paper

Pielke Sr., R.A., R. Wilby, D. Niyogi, F. Hossain, K. Dairuku, J. Adegoke, G. Kallos, T. Seastedt, and K. Suding, 2011: Dealing with complexity and extreme events using a bottom-up, resource-based vulnerability perspective. AGU Monograph on Complexity and Extreme Events in Geosciences, in press. 

By coincidence, Richard Kerr has published  the following  article in Science (h/t  to Rob Wilby)

Vital Details of Global Warming Are Eluding Forecasters

which includes text such as [highlight added]

Seattle Public Utilities officials had a question for meteorologist Clifford Mass. They were planning to install a quarter-billion dollars’ worth of storm-drain pipes that would serve the city for up to 75 years. “Their question was, what diameter should the pipe be? How will the intensity of extreme precipitation change?” Mass says. If global warming means that the past century’s rain records are no guide to how heavy future rains will be, he was asked, what could climate modeling say about adapting to future climate change? “I told them I couldn’t give them an answer,” says the University of Washington (UW), Seattle, researcher.

Other excerpts read

Although uncertainties abound, “uncertainty tends to be downplayed in a lot of [regional] modeling for adaptation,” says global modeler Christopher Bretherton of UW Seattle.

A rapidly growing community of regional modelers is turning out increasingly detailed projections of future climate, but many researchers, mostly outside the downscaling community, have serious reservations. “Many regional modelers don’t do an adequate job of quantifying issues of uncertainty,” says Bretherton, who is chairing a National Academy of Sciences study committee on a national strategy for advancing climate modeling. “We’re not confident predicting the very things people are most interested in being predicted,” such as changes in precipitation. Regional models produce strikingly detailed maps of changed climate, but they might be far off base. “The problem is that precision is often mistaken for accuracy,” Bretherton says.Battisti [meteorologist David Battisti of UW Seattle] just doesn’t see the point of downscaling. “I would never use one of these products,” he says.

Gregory Tripoli’s complaint about the global models is that they can’t create the medium-size weather systems that they should be sending into any embedded regional model. Tripoli, a meteorologist and modeler at the University of Wisconsin, Madison, cites the case of summertime weather disturbances that churn down off the Rocky Mountains and account for 80% of the Midwest’s summer rainfall. If a regional model forecasting for Wisconsin doesn’t extend to the Rockies, Wisconsin won’t get the major weather events that add up to be climate. And some atmospheric disturbances travel from as far away as Thailand to wreak havoc in the Midwest, he says, so they could never be included in the regional model.

However, despite these major deficiencies in downscaling, large amounts of funding are being spent (wasted in my view) in this approach which cannot remove the uncertainties that are systemic in the Type 4 downscaling approach as we outlined in our paper Pielke et aol 2011. Unfortunately, the downscaling of the global model predictions of impacts decades into the future has become a  money sink which is preventing funding for much more scientifically robust studies.

As the article writes at the end

The downscaling of climate projections should be getting a boost as the Coordinated Regional Climate Downscaling Experiment (CORDEX) gets up to speed. Begun in 2009, CORDEX “is really the first time we’ll get a handle on all these uncertainties,” Giorgi says. Various groups will take on each of the world’s continent-size regions. Multiple global models will be matched with multiple regional models and run multiple times to tease out the uncertainties in each. “It’s a landmark for the regional climate modeling community,” Giorgi says.

The entire article is worth reading.

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